This invention relates to methods and apparatus for providing hypothermia or effecting hemostasis to prevent hemorrhaging in organs or regions within the human body or the like.
Topical hypothermia of organs or regions within the body has been proposed in the past. Examples of such proposed systems are disclosed in U.S. Pat. Nos. 3,460,538 granted on Aug. 12, 1969 to Armstrong, 3,738,372 granted June 12, 1973 to Shioshvili and in "A Simple Cooling Circuit for Topical Cardiac Hypothermia," Thorax, Vol. 31, pp. 565-571 (1976).
Such previously proposed systems are each deficient in one or more respects. Firstly, in those systems which utilize inflatable bags, none provides means by which the bag may be distended subsequent to its location or insertion proximate the organ to be treated so that its walls are in optimal cooling contact with the walls of the organ. Secondly, in most systems the continued sterility of the coolant fluid during operation cannot be assured. Thirdly, all of the previously proposed systems include apparatus which are bulky and difficult to assemble which make them practically unsuitable for use in an operating room as well as expensive in manufacture.
Further, although it is standard procedure to lower the blood temperature during cardio-pulmonary support (such as during open heart surgery) by means of a heat exchanger incorporated into the pump-oxygenator circuitry, this systemic hypothermia, while decreasing cellular metabolism and preventing cellular damage from anoxia, will not provide hypothermic protection to the myocardium of the heart when the aorta is occluded, thereby depriving the heart and the coronary arteries of cardiopulmonary support. Generally, two methods of achieving topical cardiac hypothermia have been used. The opened pericardium has been filled with a frozen saline slush, or, alternatively, the pericardial "basin" has been irrigated along with the heart surface with cooled Lactated Ringer's solution via a drip bottle and wall suction (See Thorax article referred to hereinabove). However, neither of these methods provide direct cooling to the endocardium or inner wall of the heart. Both methods rely on introducing free fluid or slush within the open pericardium and, therefore, the patient must be appropriately positioned to maintain the cold fluid within the pericardial basin without spillage. This requirement and the usual difficulties inherent in the use of a fluid in an unconfined state render both of these techniques less desirable.
Although some surgeons have filled an open ventricle with saline slush in an attempt to cool the myocardium, this has been found to be a rather clumsy procedure involving, among other problems, the necessity for the surgeon to perform delicate surgical techniques with his fingers in an ice cold solution. Additionally, some surgeons have attempted to apply cardiac hypothermia by introducing cannulae into the openings of the coronary arteries which lie in the aortic root immediately adjacent to the heart. Cold perfusate is then pumped into the coronary arteries and retrieved by suction from the right atrium and/or coronary sinus. However, since much of the cardiac surgery is performed on these coronary arteries and in the aortic root this procedure has found only limited application and, consequently, is of limited value.